NAPERVILLE, Ill. (AP) — Neighbors heard the couple shouting at each other, but they never saw it get physical. Artur Plackowska said his wife recently told him she loved him.

But beneath that ordinary domestic facade lay far more violent resentments between the husband and wife, prosecutors say, eventually leading Elzbieta Plackowska to kill her own 7-year-old son, stabbing him 100 times Tuesday, all out of anger at her often-absent, truck driver husband. She then fatally and repeatedly stabbed a 5-year-old girl she was babysitting.

"She felt he truly did not appreciate how fine a wife and mother she was," DuPage County State's Attorney Robert Berlin said. "She told the detectives that she thought by killing (her son) Justin she would make her husband hurt the way she hurt in their relationship."

The gruesome slayings have shocked this vibrant, populous suburb 25 miles west of Chicago, leaving prosecutors, neighbors and relatives at a loss. Berlin said the 40-year-old Polish immigrant told investigators that her husband used to bring her flowers and gifts, but she resented him being home only on weekends and that she had to work as a maid, which she felt was beneath her.

For some in Naperville, it brought back painful memories of a similar horror, when Marilyn Lemak fed her three children peanut butter laced with antidepressants and suffocated them 13 years ago as revenge on her estranged husband.

"I don't understand anything that's going on," said Tim Hooper, 28, who lives in the same condominium complex as the Plackowska family and would sometimes work out with Plackowska's older son. "This is so out of the blue."

The Naperville police chief said the crime scene was the most gruesome sight he'd seen in three decades on the job.

Officials said Thursday that Plackowska ordered her son Justin and a kindergartner she was babysitting, 5-year-old Olivia Dworakowski, to kneel on a bedroom floor and pray, then stabbed them both dozens of times as they begged for their lives, striking again and again as she told her son he was going to heaven.

Plackowska killed Olivia because she had witnessed the attack on Justin, Berlin said.

Officers who forced their way inside the locked apartment hours later found blood-spattered walls and the children's bodies in a master bedroom where moments before the killings they had been happily jumping on a bed, prosecutors said.

Olivia's body was found on the bed, and Justin's was found on the floor beside it. He had stab wounds on his head, face, neck and back. Both appeared to have had their throats slit.

The slayings took place at the home of Olivia's mother, who works nights as a nurse and had left her daughter in Plackowska's care before. Plackowska also stabbed the two family dogs.

Investigators found two blood-stained knives: a steak knife in the kitchen sink and another in Plackowska's car, Berlin said.

Still covered in blood and with scratches on her hands, Plackowska drove to a Catholic church. Finding it closed, she called the church and left a message saying she had "done something bad" and needed help, Berlin said. She then went to a friend's home where her adult son was staying and said she had been robbed.

About the same time, Olivia's mother, Marta Dworakowski, returned home to discover her door locked and the babysitter's car gone. She called police to report her daughter was missing, and officers forced their way into the home.

Police took Plackowska into custody at her friend's home, and prosecutors charged her with first-degree murder late Wednesday.

Plackowska initially told investigators that an intruder had broken into the home and killed the children while she was outside smoking a cigarette. She then told investigators she was battling the devil and trying to get evil out of the children. Finally, Berlin said, she admitted she had lashed out in anger at her husband.

Plackowska's husband, Artur, denied the two were having problems.

"The day before (the killings) she told me that she loves me," he said in a brief interview with The Associated Press, before hanging up because he said he wanted to focus on giving his son a proper funeral.

However, a neighbor said he frequently heard the couple shouting at each other. "It happened once every other month," Victor Tuckenberry said.

There also were money troubles. Public records show the couple filed a Chapter 7 bankruptcy in 2009; a foreclosure in her name only was filed in 2007.

Still, Tuckenberry said Plackowska doted on her sons and he was shocked by the slayings. Plackowska and Justin "were together all the time," he said.

Plackowska arrived in the United States from her native Poland on a tourist visa 12 years ago, Berlin said. She is not a U.S. citizen and authorities were trying to verify her immigration status. Berlin said she has no prior history of violence, although she had a misdemeanor DUI about 10 years ago.

Plackowska didn't speak during Thursday's bond hearing other than to indicate she could not afford an attorney. The judge appointed a public defender.